Disconnect the power input to the computer, i.e. external supply plug and/or AA batteries. Wait 1 minute. Measure voltage across memory backup battery.
Jeff Birt -----Original Message----- From: M100 <[email protected]> On Behalf Of ExPLIT | Pawel Radomychelski Sent: Friday, October 22, 2021 12:40 PM To: [email protected] Subject: Re: [M100] NEC PC-8201 Replacement for 16X 104M Green capacitor I measured the CN1 on the powwer supply board. PIN 6 should be 5V OK PIN 3 should be -5V OK PIN 4 should be 5V OK PIN 5 should be GND OK PIN 12 should be 5V OK PIN 16 should be 6V Not OK (-0,1 / -0,2V) PIN 18 should be 9V OK Not OK (6,7V) I measured with a simple cheap multimeter between GND (PIN 5) and every PIN) So, it seems like Power board is bad? On Fri, 2021-10-22 at 12:47 -0400, Stephen Adolph wrote: > Pawel, > Black screen usually indicates a deeper problem than a cap. > +5V good? > -5V good? > activity on the CLK signal at the processor? > check that data and address are toggling @ the main ROM and RAM > sockets? > pull and reseat ROM and RAM modules? > > just a few suggestions. > Do you have something like a scope to be able to look at signals? > > > > On Fri, Oct 22, 2021 at 12:02 PM ExPLIT | Pawel Radomychelski > <[email protected]> wrote: > > Thanks Steve, > > Tried cliping it out - same issue. Just black screen (screen full of > > black pixels) > > > > Tried replace the ROM Chip - same. > > Will try to replace the cap. > > > > Thanks > > > > > > On Fri, 2021-10-22 at 09:32 -0400, Stephen Adolph wrote: > > > can you just clip it out and carry on? > > > > > > On Fri, Oct 22, 2021 at 9:10 AM ExPLIT | Pawel Radomychelski > > > <[email protected]> wrote: > > > > Hello collegues! > > > > > > > > I bought another "non-working" NEC PC-8201 (Japansese Model). > > > > Found out that one green capacitor 16X 104M is broken. > > > > Now i am looking for the modern replacement. Someone know, what > > > > modern replacment i can use? > > > > > > > > Thanks > > > > > > > > > > -- Kind regards / Mit freundlichen Grüßen ExPLIT IT Solutions Pawel Radomychelski
